The primary objective of this study is to assess the safety and maximum tolerated dose level of rhIL-12 administered by subcutaneous injection in patients with advanced malignancies. Secondary objectives of this study are: 1) To evaluate the pharmacokinetics and pharmacodynamics of rhIL-12 following multiple subcutaneous injections in patients with advanced cancer. 2) To explore the antitumor activity of rhIL-12 administered by this dosage schedule and route of administration.